Why it looks like this

In 1138 the Song dynasty, driven south, made Hangzhou its capital — Marco Polo later described it as one of the most splendid cities in the world. The city grew in the space between West Lake and the Qiantang River, and the lake was treated as a garden, not building land: poets and governors (including Su Dongpo, who built its famous causeway) kept it open.

So modern Hangzhou wraps a still-empty lake on three sides. The Grand Canal from Beijing ends here too, entering the city from the north — water fixed both edges of this map.